Electric guitar incorporating separate pickups for the wound and unwound strings



April 6, 1965 L. FENDER 3,177,283 ELECTRIC GUITAR INCORPORATING SEPARATE PICKUPS FOR THE WOUND AND UNWOUND STRINGS Filed Aug. 21, 1961 l llllll ragga ,5

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6, 45 AMPLIFIER 47- g- 49 INVENTOR.

QAEEA/(EM'A/fiffi 5'0 M Aw United States Patent 3,177,283 ELECTRIC GUITAR nscouroRAriNe SEPARATE This invention relates to an electric guitar, and to a novel compound pickup incorporated therein.

An object of the invention is to provide an electric guitar in which separate pickup means are employed for the wound strings and the unwound strings, and also incorporating electric-circuit means to adjust the electrical signals created by vibration of the unwound strings in relation to the electrical signals created by vibration of the Wound strings in order to provide a perfectly balanced and musically uniform response.

Another object is to provide a pickup means associated with the unwound strings of a guitar or the like, and electric-circuit means to control the tone of the notes generated by vibration of such unwound strings, such tone-control means being independent of the tone-control means for the wound strings.

An additional object is to provide an electric guitar incorporating electric-circuit means which permit the guitarist to achieve a perfect balance between notes produced by the wound and unwound strings, in accordance with his individual desires and preferences, such electriccircuit means permitting the guitarist to control independently the response to the unwound strings.

A further object is to provide an electric guitar incorporating separate but adjacent pickups for the wound and unwound strings, such pickups incorporating coil means which are oppositely wound relative to each other in order to eliminate hum induced by extraneous electromagnetic fields, one of such pickups incorporating tonecontrol means adapted to balance the response achieved threreby in relation to the response of the other of such pickups.

These and other objects and advantages of the invention will be more fully set forth in the following specification and claims, considered in connection with the attached drawing to which they relate.

In the drawing:

FIGURE 1 is a fragmentary plan view illustrating an .electric guitar incorporating pickup means constructed in accordance with the present invention;

FIGURE 2 is an enlarged fragmentary plan view illustrating the region of the guitar at which the pickups are located;

FIGURE 3 is a transverse sectional view taken on line 3-3 of FIGURE 2;

FIGURE 4 is a transverse sectional view taken on line 44 of FIGURE 2; and

FIGURE 5 is a schematic electric-circuit diagram illustrating the electric-circuit means for balancing the response of the pickup for the unwound strings relative to that of the pickup for the wound strings.

Referring to the drawing, an electric guitar is indicated generally at 10, having a body 11 to which is connected a neck 12. Mounted in tensioned relationship over the body and neck are a plurality of strings 13-18. Such strings are substantially parallel to each other and lie generally in a plane which is parallel to the face of the guitar body, such face being indicated at 21. The strings are stretched between a bridge assembly 22, which is mounted on the body 11, and suitable tuning screws (not shown) provided on the head (not shown) at the outer end of neck 12.

Two of the guitar strings 13-18, namely numbers 13 and 14, are unwound wires formed of a suitable magnetizable material such as steel. These are the strings which are highest in pitch. The remaining strings, namely numbers 15-18, are adapted to generate lower-pitched notes, and are constructed with magnetizable cores 24 around which windings 25 are provided. The winding 25 on each core 24 is a tight helix of a suitable magnetizable wire.

If a single pickup were employed for all of the guitar strings 13-18, and the guitarist were to play a chord by picking each of the strings with uniform pressure, the notes produced by the unwound strings 13 and 14 would be much more dominant than those generated by the wound strings 15-18. Even if the picking pressure is not uniform, the wound and unwound strings produce soundshaving audibly different characteristics. This is because the windings on the magnetizable cores of the wound strings have the effect of dampening harmonics, particularly the higher harmonics. Thus, the unwound strings produce notes which contain a much larger proportion of harmonics, in relation to the fundamental, than do notes produced by the wound strings. The notes produced by the wound and unwound strings therefore sound differently, which is a highly undesirable condition.

According to the present invention, a first electromagnetic pickup 27 is inductively associated with the wound strings 15-13, and a second electromagnetic pickup 28 is inductively associated with the unwound strings 13 and 14. These pickups are adjacent each other longitudinally of the strings, but are olfset relative to each other laterally of the strings. Electric-circuit means 29 (FIG- URE 5) are then associated with the pickup 28 for the unwound strings 13 and 14 to control the tones of the notes generated thereby in relation to the tones of the notes generated by the wound strings 15-18. A detailed description of such tone-control means, and of the electric-circuit means associated with both pickups, will be given below.

Referring particularly to FIGURES 2 and 3, the first pickup 27, for the wound strings 15-18, is illustrated to comprise a plurality of short cylindrical pole pieces or magnets 31 formed of permanent magnet material. Pole pieces 31 are disposed in a plane which is perpendicular to the plane containing the guitar strings 13-18, each pole piece being directly beneath an associated string 15-18. Like poles, such as the north poles, of all of the pole pieces 31 are disposed adjacent the plane of the strings. A single coil 32, comprising a large number of turns of fine insulated wire, is wound around all of the pole pieces 31, so that current will be induced in the coil in response to disturbances of the magnetic fields of one or more pole pieces caused by vibration of the wound strings 15-18.

A casing 33, formed of fiber, plastic or any suitable substance, is provided around the coil 32 in such relationship that the ends of the pole pieces are (preferably) exposed and are adjacent (but spaced from) the respective wound strings 15-18. Suitable means, such as screws 34, are adapted to connect the casing 33 to body 11, the casing being illustrated as disposed in a recess 35 in such body and supported upon a mass 36 of sponge rubbcr or the like. With the described construction, adjustment of the screws 34 will effect raising or lowering of the casing, together with the coil and pole pieces, to position the upper ends of thepole pieces relative to the strings. The balance and proximity of the response may thus be varied.

The second electromagnetic pickup 28, for the unwound strings, is identical to the one for the wound strings except that it is much shorter, having only two pole pieces 38 which are respectively associated with the strings 1 3 and 14. The short coil wound around the pole pieces 38 is indicated at 39. The casing is shown at 41, the adjustment screws at 42, the recess at 43 and the mass of resilient material at 44. The pole pieces 38 of the second pickup 2 8 have the same poles adjacent the strings as do the pole pieces of the first pickup, namely north in the illustrated embodiment.

Proceeding next to a detailed description of FIGURE 5, the electric-circuit means 29 to control the tone of notes generated by the pickup 28 comprises a capacitor 46 and variable resistor 47 which are connected in seriescircuit relationship between the terminals of coil 39. One terminal of such coil (the one adjacent capacitor 46) is grounded, as indicated at 48, the other terminal being connected to one terminal of coil 32 of pickup 27.

The remaining terminal of coil 32 for the wound strings (pickup Z7) is connected both to a tone-control means'and to a volume-control means. The tone-control means is illustrated to comprise a variable resistor 49 and a capacitor 50 connected in series-circuit relationship between coil 32 and ground. The volume-control means comprises the winding of a potentiometer Sll, such winding being connected between the coil and ground. The sliding tap of the potentiometer is connected to one input terminal of a suitable amplifier 52', the other input terminal of the amplifier being grounded. The. output of the amplifier is connected to a suitable loudspeaker 53.

The capacitors 46 and 50 have values such that they will transmit the higher-frequency components with relative ease, but will substantially block the lower-frequency components. Capacitor 46, for example, may have a value of 0.02 mic'rofarads. Resistor 47 (a type having an audio taper) may have a value of 50,000 ohms.

It is emphasized that the short coil 39 is wound in a direction opposite to the direction of winding of coil 32. Thus, the voltages induced in such coils by extraneous electromagnetic fields, such as are created by fluorescent lights, will tend to cancel each other. For this reason, the present pickup means is relatively insensitive to hum resulting from such extraneous fields.

Operation- In the operation of the present guitar and pickup means, the guitarist adjusts the first-mentioned variable resistor 47 in order to regulate the response to vibration of the unwound strings l3 and 14 in relation to the response to vibration of the wound "strings 15-18. When the resistor '47 is set to a relatively high value, picking of the unwound strings 13 and 14 produces in the amplifier and loudspeaker a response containing strong harmonics. On the other hand, when the resistor 47 is set to a low value, the relatively high-frequency components generated in coil'39 are shunted through the capacitor 46 and do not reach the amplifier and loudspeaker. The response to vibration of the unwound strings is then relatively weak, particularly. insofar as the higher harmonics are concerned. The response is thus balanced relative to the response to the unwound strings which, as explained above, contain harmonics which are weak inv relation to the fundamentals.

After the guitarist has achieved the desired balance between the response to the unwound strings and that to the wound strings, through manipulation of the variable resistor 47, he adjusts the variable resistor 49 and the potentiometer 51 in order to vary the response of the entire pickup apparatus (comprising both pickups 27 and 28). When resistor 49 is set to a low value, the higherfrequency components are shunted through capacitor to ground, and therefore do not appear in the amplifier and loudspeaker. When the sliding tap of the potentiometer 51 is set so that it is relatively adjacent the coil 32, thevolume is high since all or substantially all of the voltage across the potentiometer winding is transmitted to the amplifierand loudspeaker. On the other hand, when the slider of the potentiometer is relatively adjacent ground, only a small part of the voltage in the potentiometer winding appears in the amplifier and loudspeaker, so that the volume is low.

it will thus be appreciated that the present circuit, although economical and relatively simple, produces the distinct and important advantages that the response to the unwound strings may be balanced relative to the response to the wound strings, through the mere manipulation of an electrical control. Furthermore, the over-all tone and volume of the circuit may be readily varied, and the sensitivity of the circuit to hum is minimized.

It is to be understood that the two'pickups, that is to say all six (or more) pole pieces, may be caused to lie along a singlestraight line instead of along two offset lines. Stated otherwise, the pickup 28 may be mounted in axial alignment with pickup 27.

Various embodiments of the present invention, in addition to what has been illustrated and described in detail, may be employed without departing from the scope of the accompanying claims.

I claim:

1. An electrical musical instrument of the guitar type, which comprises a body, a plurality of strings mounted over'said body in tensioned relationship, certain of said strings being provided with windings therearound, at least one of said strings being free of a winding, pickup means operatively associated with said strings to convert into electrical signals the vibrations resulting from picking thereof, and electric-circuit means operatively associated with said pickup means to balance relative to each other the electrical signal produced by said pickup means due to vibration of said one string and the electrical signals produced by said pickup means due to vibration of said certain strings, said pickup means comprising a first electromagnetic pickup operatively associated with said certain strings and a second electromagnetic pickup operatively associated with said one string, said electric-circuit means comprising a tone-control circuit operatively associated with said second pickup only, said tone-control circuit including a variable circuit element adapted to efiect progressive tone variation.

2. An electrical musical instrument of the guitar type, which comprises a body, a plurality of strings mounted over said body in tensioned relationship, certain of said strings being provided with windings therearou-nd, at least one of said strings being free of a winding, pickup means operatively associated with said strings to convert into electrical signals the vibrations resulting from picking thereof, and electric-circuit means operatively associated with said pickup means to balance relative to each other the electrical signal produced by said pickup means due to vibration of said one string and the electrical signals produced by said pickup means due to vibration of said certain strings, said electric-circuit means comprising a tone-control circuit adapted to weaken the harmonics, relative to the fundamental, in the electrical signal produced by said pickup means dueto vibr'ationot said one string, said tone-control circuit including a variable circuit element adapted to elfect progressive tone variations.

3. An electrical musical instrument of the guitar type, which comprises a body, a plurality of strings mounted over said body in tensioned relationship, certain of said strings being provided. with windings therearound, at

' least one of said strings being free or" a winding, pickup means operatively associated with said strings to convert into electrical signals the vibrations resulting from picking thereof, and electric-circuit means operatively associated with said pickup means to balance relative to'each other the electrical signal produced by said pickup means due to vibration of said one string and the electrical signals produced by said pickup means due to vibration of said certain strings, said pickup means comprising a first electromagnetic pickup operatively associated with said certain strings and a second. electromagnetic pickup operatively associated with said one string, each of said pickups comprising at least one permanent-magnet pole piece inductively associated with each string with which the pickup is related, each of said pickups further comprising a coil of wire wound around such pole pieces to generate voltage in response to variation of the fields of said pole pieces due to disturbances thereof caused by vibration of the associated strings, said coils of said first and second pickups being connected to each other in series-circuit relationship, said electric-circuit means cornprising progressively and continuously-variable tone-control means connected to the coil of said second pickup.

4. The invention as claimed in claim 3, in which said series-connected coils are Wound in opposite directions to elfect at least partial cancellation of voltages generated therein by extraneous electromagnetic fields.

5. The invention as claimed in claim 3, in which an amplifier and loudspeaker are connected to the output of the series combination of said coils of said first and sec- 0nd pickups, and in which tone and volume-control means are operatively associated with said series combination of the coils of said first and second pickups to vary the response to vibration of all of said strings.

6. An electric guitar, which comprises a body having a face, a plurality of strings mounted over said body in tensioned relationship, said strings being generally parallel to each other and lying in a plane which is generally parallel to said face, the majority of said strings being formed with magnetizable cores having tightly-wound helical windings therearound, the minority of said strings being formed of magnetizable wire and free of windings, said minority of strings being adapted to generate relatively high-pitched notes, a first electromagnetic pickup mounted on said body and operatively associated with said majority of strings to convert into electrical signals the vibrations thereof, a second electromagnetic pickup mounted on said body and operatively associated with said minority of strings to convert into electrical signals the vibrations thereof, said first pickup comprising a plurality of permanent-magnet pole pieces respectively associated with said strings of said majority thereof and a coil of wire wound around said pole pieces to generate electric signals in response to disturbance of the fields of said pole pieces caused by vibration of said strings in said majority thereof, said second pickup comprising a plurality of permanent magnet pole pieces operatively associated with the strings in said minority thereof and a coil of wire wound around said pole pieces to generate electrical signals in response to disturbance of the fields of said pole pieces caused by vibration of said strings in said minority thereof, amplifier and loudspeaker means connected to said coils of said first and second pickups to convert into sound the electrical signals generated by said pickups in response to vibration of all of said strings, and tone-control means operatively associated only with the coil of said second pickup to change the sound produced by said amplifier and loudspeaker means in response to vibration of said minority of said strings relative to the sound generated by said amplifier and loudspeaker means in response to vibration of said majority of said strings.

7. The invention as claimed in claim 6, in which said tone-control means comprises a capacitor and a variable resistor connected to each other in series-circuit relation ship, the series combination of said capacitor and variable resistor being connected across said coil of said second pickup.

8. The invention as claimed in claim 6, in which tone and volume control means are connected to said coils of said first and second pickups to change the sound produced by said amplifier and loudspeaker means in response to vibration of all of said strings.

9. The invention as claimed in claim 6, in which said first and second pickups are disposed relatively adjacent each other longitudinally of said strings, and are ofiset relative to each other laterally of said strings.

10. The invention as claimed in claim 6, in which each of said pickups is provided with a casing around said coil and pole pieces thereof, in which said casing is mounted in a recess in said body, and in which means are provided to adjust the distance from said casing to said strings.

11. The invention as claimed in claim 6, in which said coils of said first and second pickups are wound in opposite directions relative to each other, and are connected in series, thereby effecting at least partial cancellation of voltages induced by extraneous electromagnetic fields.

References Cited by the Examiner UNITED STATES PATENTS 2,784,631 3/57 Fender 841.15 2,817,261 12/57 Fender 841.16 2,896,491 7/59 Lover 841.l5 2,897,709 8/59 McCarty 841.16 2,95 8,249 11/60 Michalek et a1 841.16 2,976,755 3/61 Fender 84-1.16 2,989,884 6/61 Bunker 84-1.16

FOREIGN PATENTS 588,178 5/47 Great Britain.

OTHER REFERENCES Culver, Musical Acoustics (text), 4th edition, 1956, McGraW-Hill (pages and 147).

ARTHUR GAUSS, Primary Examiner. CARL W. ROBINSON, Examiner. 

1. AN ELECTRICAL MUSICAL INSTRUMENT OF THE GUITAR TYPE, WHICH COMPRISES A BODY, A PLURALITY OF STRINGS MOUNTED OVER SAID BODY IN TENSIONED RELATIONSHIP, CERTAIN OF SAID STRINGS BEING PROVIDED WITH WINDINGS THEREAROUND, AT LEAST ONE OF SAID STRINGS BEING FREE OF A WINDING, PICKUP MEANS OPERATIVELY ASSOCIATED WITH SAID STRINGS TO CONVERT INTO ELECTRICAL SIGNALS THE VIBRATIONS RESULTING FROM PICKING THEREOF, AND ELECTRIC-CIRCUIT MEANS OPERATIVELY ASSOCIATED WITH SAID PICKUP MEANS TO BALANCE RELATIVE TO EACH OTHER THE ELECTRICAL SIGNAL PRODUCED BY SAID PICKUP MEANS DUE TO VIBRATION OF SAID ONE STRING AND THE ELECTRICAL SIGNALS PRODUCED BY SAID PICKUP MEANS DUE TO VIBRATION OF SAID CERTAIN STRINGS, SAID PICKUP MEANS COMPRISING A FIRST ELECTROMAGNETIC PICKUP OPERATIVELY ASSOCIATED WITH SAID CERTAIN STRINGS AND A SECOND ELECTROMAGNETIC PICKUP OPERATIVELY ASSOCIATED WITH SAID ONE STRING, SAID ELECTRIC-CIRCUIT MEANS COMPRISING A TONE-CONTROL CIRCUIT OPERATIVELY ASSOCIATED WITH SAID SECOND PICKUP ONLY, SAID TONE-CONTROL CIRCUIT INCLUDING A VARIABLE CIRCUIT ELEMENT ADAPTED TO EFFECT PROGRESSIVE TONE VARIATION. 